The present invention relates to an adjustable headrest for dental chairs and more specifically to such a headrest which can be operated with one hand.
Most present type adjustable headrests known in the art need both hands to operate, one hand to hold the headrest in a selected position and the other hand to operate the locking mechanism. For various reasons it is advantageous to have the headrest operable with one hand so that the dentist will have one hand free to hold an instrument, the head of the patient or for various other purposes.
Headrests are known, which are operable with one hand, as for example the headrest shown in U.S. Pat. No. 3,817,576. One drawback of such a headrest of the prior art is that a pawl mechanism used to lock the headrest limits positioning to a relatively few predetermined positions throughout the range of movement. Also, the headrest and the lever for operating the lock mechanisms are pivotable about different points which results in a relative movement between the headrest and lever during repositioning. In some instances this relative movement makes the headrest awkward to operate.
In the presently available headrests, the pivot point of the headrest is close to the joint between the patient's head and neck, that is near the plane of the oral cavity. As a result, when the headrest is rotated, the head simply rotates on the neck column. Since the radius length defined by the distance between the pivot point of the headrest and the oral cavity is relatively short, the position of the patient's oral cavity does not significantly change.
In the articulated headrest of the present invention the lock mechanism for operation is contained in the headrest. Disengagement of the lock and repositioning the headrest is accomplished by operating a bar at the back of the headrest with the fingers of one hand while articulating the headrest with the same hand up or down to get the desired position. Releasing the bar then locks the headrest in that particular position. The locking mechanism used in the present invention not only permits a greater freedom in positioning of the headrest within its range of movement but also is readily accessible to both the dentist or hygienist regardless of whether the patient is in a supine or upright position and regardless of whether the dentist or hygienist is at the left or right side of the dental chair.
Further, in the present invention, the pivot point of the headrest is located not near the patient's mouth but well below the patient's occipital such that it closely coincides with the actual pivot point of a patient's neck. As a result, when the headrest is articulated, the patient's entire neck column is bent. Since the radius length defined by the distance between the pivot point of the headrest and the oral cavity is now relatively long, the patient's oral cavity tends to rotate a greater distance for better visibility to the dentist.
As an added feature, the headrest includes a bracket which can be used to hold instruments and their accessories.